U.S. patent number 8,155,712 [Application Number 11/726,874] was granted by the patent office on 2012-04-10 for low power very high-data rate device.
This patent grant is currently assigned to SIBEAM, Inc.. Invention is credited to James P. K. Gilb, Jeffrey M. Gilbert, Sheung Li, Karim Nassiri-Toussi.
United States Patent |
8,155,712 |
Gilb , et al. |
April 10, 2012 |
Low power very high-data rate device
Abstract
A radio frequency (RF) transmitter has a plurality of digitally
controlled phased array antennas coupled to and controlled by the
processor to transmit data. The processor is to enable one or more
antennas to be turned off during a use of the apparatus to reduce a
power consumption of the apparatus.
Inventors: |
Gilb; James P. K. (San Deigo,
CA), Gilbert; Jeffrey M. (Palo Alto, CA), Li; Sheung
(Mountain View, CA), Nassiri-Toussi; Karim (Belmont,
CA) |
Assignee: |
SIBEAM, Inc. (Sunnyvale,
CA)
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Family
ID: |
38476947 |
Appl.
No.: |
11/726,874 |
Filed: |
March 22, 2007 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20070224951 A1 |
Sep 27, 2007 |
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Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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60785824 |
Mar 23, 2006 |
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Current U.S.
Class: |
455/574;
455/127.5; 455/343.1 |
Current CPC
Class: |
H04W
52/287 (20130101); H04B 7/0691 (20130101); H01Q
3/26 (20130101); H04W 52/42 (20130101); H04B
7/0617 (20130101) |
Current International
Class: |
H04B
1/38 (20060101) |
Field of
Search: |
;455/562.1,574,575.7,103,127.1,127.2,127.3,127.5,343.1 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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1746735 |
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Jan 2007 |
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EP |
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WO 95/26116 |
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Sep 1995 |
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WO |
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WO 2005/048486 |
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May 2005 |
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WO |
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Other References
European Office Action for European Patent Application No.
07753954.2, Dec. 30, 2009, 4 Pgs. cited by other .
Notification of Transmittal of the International Search Report and
the Written Opinion, for PCT/US2007/007370, mailed Oct. 17, 2008,
pp. 21 total. cited by other .
Notification concerning Transmittal of International Preliminary
Report on Patentability, for PCT/US2007/007370, mailed Dec. 11,
2008, pp. 12 total. cited by other.
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Primary Examiner: Vo; Nguyen
Attorney, Agent or Firm: Blakely, Sokoloff, Taylor &
Zafman LLP
Parent Case Text
RELATED APPLICATIONS
This application claims the benefit of U.S. Provisional Application
No. 60/785,824 filed on Mar. 23, 2006, the contents of which are
incorporated herein by reference.
Claims
We claim:
1. An apparatus comprising: a processor; and a radio frequency (RF)
transmitter having a plurality of digitally controlled phased array
antennas coupled to and controlled by the processor to transmit
data, wherein the processor is to enable one or more antennas to be
turned off during a use of the apparatus to reduce power
consumption of the apparatus, the one or more antennas turned off
based on at least one of i) a data rate at the apparatus being
above a first predetermined threshold and a signal quality of data
at the apparatus being above a second predetermined threshold, and
ii) a feedback of a data rate at another location being above a
third threshold and a signal quality at a device at another
location being above a fourth predetermined threshold.
2. The apparatus of claim 1 further comprising a plurality of power
amplifiers corresponding to the plurality of digitally controlled
phased array antennas.
3. The apparatus of claim 2 wherein the processor is to turn off a
power amplifier associated with an antenna to be turned off.
4. The apparatus of claim 1 wherein one or more antennas are turned
off when the power source of the apparatus is a battery.
5. The apparatus of claim 1 wherein all antennas are turned on when
the power source of the apparatus is an AC power supply.
6. An apparatus comprising: a processor; and a radio frequency (RF)
transmitter having a plurality of digitally controlled phased array
antennas coupled to and controlled by the processor to transmit
data, wherein the processor is to enable one or more antennas to be
turned off during a use of the apparatus to reduce power
consumption of the apparatus, wherein the number of antennas to be
turned off is based on a data rate at the apparatus being above a
first predetermined threshold and a signal quality of data at the
apparatus being above a second predetermined threshold.
7. An apparatus comprising: a processor; and a radio frequency (RF)
transmitter having a plurality of digitally controlled phased array
antennas coupled to and controlled by the processor to transmit
data, wherein the processor is to enable one or more antennas to be
turned off during a use of the apparatus to reduce power
consumption of the apparatus, wherein the number of antennas to be
turned off is based on a feedback of a data rate at a device at
another location being above a first predetermined threshold and a
signal quality at the device at the another location being above a
second predetermined threshold.
8. An apparatus comprising: a processor; and a radio frequency (RF)
transmitter having a plurality of digitally controlled phased array
antennas coupled to and controlled by the processor to transmit
data, wherein the processor is to enable one or more antennas to be
turned off during a use of the apparatus to reduce power
consumption of the apparatus, wherein one or more selected antennas
to be turned off are based on a data rate at the apparatus being
above a first predetermined threshold and a signal quality of data
at the apparatus being above a second predetermined threshold.
9. An apparatus comprising: a processor; and a radio frequency (RF)
transmitter having a plurality of digitally controlled phased array
antennas coupled to and controlled by the processor to transmit
data, wherein the processor is to enable one or more antennas to be
turned off during a use of the apparatus to reduce power
consumption of the apparatus, wherein one or more selected antennas
to be turned off are based on a feedback of a data rate at a device
at another location being above a first predetermined threshold and
a signal quality at the device at the another location being above
a second predetermined threshold.
10. A method comprising: detecting a power source of a wireless
device, the wireless device comprising a processor and a radio
frequency (RF) transmitter having a plurality of digitally
controlled phased array antennas coupled to and controlled by the
processor to transmit data; and enabling one or more antennas to be
turned off during a use of the wireless device based on the power
source to reduce power consumption of the wireless device, the one
or more antennas turned off based on at least one of i) a data rate
at the wireless device being above a first predetermined threshold
and a signal quality of data at the wireless device being above a
second predetermined threshold, and ii) a feedback of a data rate
at another wireless device at another location being above a third
predetermined threshold and a signal quality at another wireless
device at another location being above a fourth predetermined
threshold.
11. The method of claim 10 wherein the wireless device further
comprises a plurality of power amplifiers corresponding to the
plurality of digitally controlled phased array antennas.
12. The method of claim 11 further comprising: turning off a power
amplifier associated with an antenna to be turned off.
13. The method of claim 10 further comprising: turning off one or
more antennas when the power source of the wireless device is a
battery.
14. The method of claim 10 further comprising: turning on all
antennas when the power source of the wireless device is an AC
power supply.
15. A method comprising: detecting a power source of a wireless
device, the wireless device comprising a processor and a radio
frequency (RF) transmitter having a plurality of digitally
controlled phased array antennas coupled to and controlled by the
processor to transmit data; enabling one or more antennas to be
turned off during a use of the wireless device based on the power
source to reduce power consumption of the wireless device; and
turning off a number of antennas based on a data rate at the
wireless device being above a first predetermined threshold and a
signal quality of data at the wireless device being above a second
predetermined threshold.
16. A method comprising: detecting a power source of a wireless
device, the wireless device comprising a processor and a radio
frequency (RF) transmitter having a plurality of digitally
controlled phased array antennas coupled to and controlled by the
processor to transmit data; enabling one or more antennas to be
turned off during a use of the wireless device based on the power
source to reduce power consumption of the wireless device; and
turning off a number of antennas based on a feedback of a data rate
at another wireless device being above a first predetermined
threshold and a signal quality at the another wireless device at
the another location being above a second predetermined
threshold.
17. A method comprising: detecting a power source of a wireless
device, the wireless device comprising a processor and a radio
frequency (RF) transmitter having a plurality of digitally
controlled phased array antennas coupled to and controlled by the
processor to transmit data; enabling one or more antennas to be
turned off during a use of the wireless device based on the power
source to reduce power consumption of the wireless device; and
selecting one or more antennas to be turned off based on a data
rate at the wireless device being above a first predetermined
threshold and a signal quality of data at the wireless device being
above a second predetermined threshold.
18. A method comprising: detecting a power source of a wireless
device, the wireless device comprising a processor and a radio
frequency (RF) transmitter having a plurality of digitally
controlled phased array antennas coupled to and controlled by the
processor to transmit data; enabling one or more antennas to be
turned off during a use of the wireless device based on the power
source to reduce power consumption of the wireless device; and
selecting one or more antennas to be turned off based on a feedback
of a data rate at another location being above a first
predetermined threshold and a signal quality at the another
wireless device at the another location being above a second
predetermined threshold.
19. A program non-transitory tangible storage device readable by a
machine, tangibly embodying a program of instructions executable by
the machine to perform a method, the method including: detecting a
power source of a wireless device, the wireless device comprising a
processor and a radio frequency (RF) transmitter having a plurality
of digitally controlled phased array antennas coupled to and
controlled by the processor to transmit data; and enabling one or
more antennas to be turned off during a use of the wireless device
based on at least one of i) a data rate at the wireless device
being above a first predetermined threshold and a signal quality of
data at the wireless device being above a second predetermined
threshold, and ii) a feedback of a data rate at another location
being above a third predetermined threshold and a signal quality at
a device at another location being above a fourth predetermined
threshold to reduce a power consumption of the wireless device.
20. The program non-transitory tangible storage device of claim 19
wherein the wireless device further comprises a plurality of power
amplifiers corresponding to the plurality of digitally controlled
phased array antennas.
21. The program non-transitory tangible storage device of claim 19
wherein the method further comprises: turning off a power amplifier
associated with an antenna to be turned off.
22. An wireless transceiver comprising: a plurality of adaptive
beamforming antennas to transmit data; and a processor coupled to
the plurality of antennas to enable one or more antennas to be
turned off to reduce power consumption of the wireless transceiver
while maintaining a minimum predetermined signal quality threshold,
the one or more antennas turned off based on at least one of i) a
data rate at the wireless transceiver being above a first
predetermined threshold and a signal quality of data at the
wireless transceiver being above a second predetermined threshold,
and ii) a feedback of a data rate at a device at another location
being above a third predetermined threshold and a signal quality at
a device at another location being above a fourth predetermined
threshold.
Description
FIELD OF THE INVENTION
The present invention relates to the field of wireless
communication; more particularly, the present invention relates to
low power very high data rate wireless communication device that
uses adaptive beamforming.
BACKGROUND OF THE INVENTION
Consumer electronic (CE) wireless devices may belong to two types:
fixed CE wireless devices and mobile CE wireless devices. Fixed CE
wireless devices may be found located in a remote or enclosed area
such as behind doors of an entertainment center. Fixed CE wireless
devices thus need to have a longer range because of the obstacles.
However, fixed CE wireless devices have essentially unlimited power
available since there are powered by an AC power source.
Mobile CE wireless devices are typically closer and can be moved
around to improve a wireless quality link. However, mobile CE
wireless devices operate with a finite amount of stored energy in a
battery and have a maximum power level.
SUMMARY OF THE INVENTION
Radio frequency (RF) transmitter and receiver have a plurality of
digitally controlled phased array antennas coupled to and
controlled by the processor to transmit or receive data. The
processor is to enable one or more antennas to be turned off during
a use of the apparatus to reduce a power consumption of the
apparatus. The selection and number of antennas to be turned off
may be based on a user selection, a type of power source connected
to the transmitter and/or receiver, or a feedback of data rate and
signal quality, among others.
BRIEF DESCRIPTION OF THE DRAWINGS
The present invention will be understood more fully from the
detailed description given below and from the accompanying drawings
of various embodiments of the invention, which, however, should not
be taken to limit the invention to the specific embodiments, but
are for explanation and understanding only.
FIG. 1 is a block diagram of one embodiment of a communication
system.
FIG. 2 is a more detailed block diagram of one embodiment of the
communication system.
FIG. 3 is a block diagram of one embodiment of a peripheral
device.
FIG. 4 is a flow diagram of one embodiment of a method for reducing
a power consumption of a wireless device using a portion of the
antennas of the wireless device based on the power source of the
wireless device.
FIG. 5 is a flow diagram of one embodiment of a method for reducing
a power consumption of a wireless device using a portion of the
antennas of the wireless device based on a user selection.
FIG. 6 is a flow diagram of one embodiment of a method for reducing
a power consumption of a wireless device using a portion of the
antennas of the wireless device based on a received data rate and
signal quality.
FIG. 7 is a flow diagram of one embodiment of a method for reducing
a power consumption of a wireless device using a portion of the
antennas of the wireless device based on a feedback of data rate
and signal quality.
FIG. 8 is a flow diagram of one embodiment of a method for reducing
a power consumption of a wireless device using specific antennas of
the wireless device based on a received data rate and signal
quality.
FIG. 9 is a flow diagram of one embodiment of a method for reducing
a power consumption of a wireless device using specific antennas of
the wireless device based on a feedback of data rate and signal
quality.
FIG. 10 is a flow diagram of another embodiment of a method for
reducing a power consumption of a wireless device using data rate
reduction, or partial transmission of the data, based on the power
source of the wireless device.
FIG. 11 is a flow diagram of another embodiment of a method for
reducing a power consumption of a wireless device using data rate
reduction, or partial transmission of the data, based on a user
selection.
FIG. 12 is a flow diagram of another embodiment of a method for
reducing a power consumption of a wireless device using data rate
reduction, or partial transmission of the data, based on a feedback
of data rate and signal quality.
DETAILED DESCRIPTION OF THE PRESENT INVENTION
An apparatus and method for wireless communication is disclosed. In
one embodiment, the wireless communication occurs using a wireless
transceiver with an adaptive beamforming antenna. As would be
apparent to one skilled in the art, the wireless communication
could occur with a wireless receiver or transmitter.
In one embodiment, the power consumption of the wireless
transceiver may be reduced by using only a portion of the antennas
in the wireless transceiver. In accordance with another embodiment,
the power consumption of the wireless transceiver may also be
reduced by transmitting only a portion of the data, or by
transmitting with a reduced data rate.
In the following description, numerous details are set forth to
provide a more thorough explanation of the present invention. It
will be apparent, however, to one skilled in the art, that the
present invention may be practiced without these specific details.
In other instances, well-known structures and devices are shown in
block diagram form, rather than in detail, in order to avoid
obscuring the present invention.
Some portions of the detailed descriptions which follow are
presented in terms of algorithms and symbolic representations of
operations on data bits within a computer memory. These algorithmic
descriptions and representations are the means used by those
skilled in the data processing arts to most effectively convey the
substance of their work to others skilled in the art. An algorithm
is here, and generally, conceived to be a self-consistent sequence
of steps leading to a desired result. The steps are those requiring
physical manipulations of physical quantities. Usually, though not
necessarily, these quantities take the form of electrical or
magnetic signals capable of being stored, transferred, combined,
compared, and otherwise manipulated. It has proven convenient at
times, principally for reasons of common usage, to refer to these
signals as bits, values, elements, symbols, characters, terms,
numbers, or the like.
It should be borne in mind, however, that all of these and similar
terms are to be associated with the appropriate physical quantities
and are merely convenient labels applied to these quantities.
Unless specifically stated otherwise as apparent from the following
discussion, it is appreciated that throughout the description,
discussions utilizing terms such as "processing" or "computing" or
"calculating" or "determining" or "displaying" or the like, refer
to the action and processes of a computer system, or similar
electronic computing device, that manipulates and transforms data
represented as physical (electronic) quantities within the computer
system's registers and memories into other data similarly
represented as physical quantities within the computer system
memories or registers or other such information storage,
transmission or display devices.
The present invention also relates to an apparatus for performing
the operations herein. This apparatus may be specially constructed
for the required purposes, or it may comprise a general purpose
computer selectively activated or reconfigured by a computer
program stored in the computer. Such a computer program may be
stored in a computer readable storage medium, such as, but is not
limited to, any type of disk including floppy disks, optical disks,
CD-ROMs, and magnetic-optical disks, read-only memories (ROMs),
random access memories (RAMs), EPROMs, EEPROMs, magnetic or optical
cards, or any type of media suitable for storing electronic
instructions, and each coupled to a computer system bus.
The algorithms and displays presented herein are not inherently
related to any particular computer or other apparatus. Various
general purpose systems may be used with programs in accordance
with the teachings herein, or it may prove convenient to construct
more specialized apparatus to perform the required method steps.
The required structure for a variety of these systems will appear
from the description below. In addition, the present invention is
not described with reference to any particular programming
language. It will be appreciated that a variety of programming
languages may be used to implement the teachings of the invention
as described herein.
A machine-readable medium includes any mechanism for storing or
transmitting information in a form readable by a machine (e.g., a
computer). For example, a machine-readable medium includes read
only memory ("ROM"); random access memory ("RAM"); magnetic disk
storage media; optical storage media; flash memory devices;
electrical, optical, acoustical or other form of propagated signals
(e.g., carrier waves, infrared signals, digital signals, etc.);
etc.
An Example of a Communication System
FIG. 1 is a block diagram of one embodiment of a communication
system. Referring to FIG. 1, the system comprises media receiver
100, a media receiver interface 102, a transmitting device 140, a
receiving device 141, a media player interface 113, a media player
114 and a display 115.
Media receiver 100 receives content from a source (not shown). In
one embodiment, media receiver 100 comprises a set top box. The
content may comprise baseband digital video, such as, for example,
but not limited to, content adhering to the HDMI or DVI standards.
In such a case, media receiver 100 may include a transmitter (e.g.,
an HDMI transmitter) to forward the received content.
Media receiver 101 sends content 101 to transmitter device 140 via
media receiver interface 102. In one embodiment, media receiver
interface 102 includes logic that converts content 101 into HDMI
content. In such a case, media receiver interface 102 may comprise
an HDMI plug and content 101 is sent via a wired connection;
however, the transfer could occur through a wireless connection. In
another embodiment, content 101 comprises DVI content.
In one embodiment, the transfer of content 101 between media
receiver interface 102 and transmitter device 140 occurs over a
wired connection; however, the transfer could occur through a
wireless connection.
Transmitter device 140 wirelessly transfers information to receiver
device 141 using two wireless connections. One of the wireless
connections is through a phased array antenna with adaptive
beamforming. The other wireless connection is via wireless
communications channel 107, referred to herein as the back channel.
In one embodiment, wireless communications channel 107 is
uni-directional. In an alternative embodiment, wireless
communications channel 107 is bi-directional.
Receiver device 141 transfers the content received from transmitter
device 140 to media player 114 via media player interface 113. In
one embodiment, the transfer of the content between receiver device
141 and media player interface 113 occurs through a wired
connection; however, the transfer could occur through a wireless
connection. In one embodiment, media player interface 113 comprises
an HDMI plug. Similarly, the transfer of the content between media
player interface 113 and media player 114 occurs through a wired
connection; however, the transfer could occur through a wireless
connection.
Media player 114 causes the content to be played on display 115. In
one embodiment, the content is HDMI content and media player 114
transfer the media content to display via a wired connection;
however, the transfer could occur through a wireless connection.
Display 115 may comprise a plasma display, an LCD, a CRT, etc.
Note that the system in FIG. 1 may be altered to include a DVD
player/recorder in place of a DVD player/recorder to receive, and
play and/or record the content.
In one embodiment, transmitter 140 and media receiver interface 102
are part of media receiver 100. Similarly, in one embodiment,
receiver 140, media player interface 113, and media player 114 are
all part of the same device. In an alternative embodiment, receiver
140, media player interface 113, media player 114, and display 115
are all part of the display. An example of such a device is shown
in FIG. 3.
In one embodiment, transmitter device 140 comprises a processor
103, an optional baseband processing component 104, a phased array
antenna 105, and a wireless communication channel interface 106.
Phased array antenna 105 comprises a radio frequency (RF)
transmitter having a digitally controlled phased array antenna
coupled to and controlled by processor 103 to transmit content to
receiver device 141 using adaptive beamforming.
In one embodiment, receiver device 141 comprises a processor 112,
an optional baseband processing component 111, a phased array
antenna 110, and a wireless communication channel interface 109.
Phased array antenna 110 comprises a radio frequency (RF)
transmitter having a digitally controlled phased array antenna
coupled to and controlled by processor 112 to receive content from
transmitter device 140 using adaptive beamforming.
In one embodiment, processor 103 generates baseband signals that
are processed by baseband signal processing 104 prior to being
wirelessly transmitted by phased array antenna 105. In such a case,
receiver device 141 includes baseband signal processing to convert
analog signals received by phased array antenna 110 into baseband
signals for processing by processor 112. In one embodiment, the
baseband signals are orthogonal frequency division multiplex (OFDM)
signals. In one embodiment, the baseband signals are single carrier
phase, amplitude, or both phase and amplitude modulated
signals.
In one embodiment, transmitter device 140 and/or receiver device
141 are part of separate transceivers.
Transmitter device 140 and receiver device 141 perform wireless
communication using phased array antenna with adaptive beamforming
that allows beam steering. Beamforming is well known in the art. In
one embodiment, processor 103 sends digital control information to
phased array antenna 105 to indicate an amount to shift one or more
phase shifters in phased array antenna 105 to steer a beam formed
thereby in a manner well-known in the art. Processor 112 uses
digital control information as well to control phased array antenna
110. The digital control information is sent using control channel
121 in transmitter device 140 and control channel 122 in receiver
device 141. In one embodiment, the digital control information
comprises a set of coefficients. In one embodiment, each of
processors 103 and 112 comprises a digital signal processor.
Wireless communication link interface 106 is coupled to processor
103 and provides an interface between wireless communication link
107 and processor 103 to communicate antenna information relating
to the use of the phased array antenna and to communicate
information to facilitate playing the content at another location.
In one embodiment, the information transferred between transmitter
device 140 and receiver device 141 to facilitate playing the
content includes encryption keys sent from processor 103 to
processor 112 of receiver device 141 and one or more
acknowledgments from processor 112 of receiver device 141 to
processor 103 of transmitter device 140.
Wireless communication link 107 also transfers antenna information
between transmitter device 140 and receiver device 141. During
initialization of the phased array antennas 105 and 110, wireless
communication link 107 transfers information to enable processor
103 to select a direction for the phased array antenna 105. In one
embodiment, the information includes, but is not limited to,
antenna location information and performance information
corresponding to the antenna location, such as one or more pairs of
data that include the position of phased array antenna 110 and the
signal strength of the channel for that antenna position. In
another embodiment, the information includes, but is not limited
to, information sent by processor 112 to processor 103 to enable
processor 103 to determine which portions of phased array antenna
105 to use to transfer content.
When the phased array antennas 105 and 110 are operating in a mode
during which they may transfer content (e.g., HDMI content),
wireless communication link 107 transfers an indication of the
status of communication path from the processor 112 of receiver
device 141. The indication of the status of communication comprises
an indication from processor 112 that prompts processor 103 to
steer the beam in another direction (e.g., to another channel).
Such prompting may occur in response to interference with
transmission of portions of the content. The information may
specify one or more alternative channels that processor 103 may
use.
In one embodiment, the antenna information comprises information
sent by processor 112 to specify a location to which receiver
device 141 is to direct phased array antenna 110. This may be
useful during initialization when transmitter device 140 is telling
receiver device 141 where to position its antenna so that signal
quality measurements can be made to identify the best channels. The
position specified may be an exact location or may be a relative
location such as, for example, the next location in a predetermined
location order being followed by transmitter device 140 and
receiver device 141.
In one embodiment, wireless communications link 107 transfers
information from receiver device 141 to transmitter device 140
specifying antenna characteristics of phased array antenna 110, or
vice versa.
An Example of a Transceiver Architecture
FIG. 2 is a block diagram of one embodiment of an adaptive beam
forming multiple antenna radio system containing transmitter device
140 and receiver device 141 of FIG. 1. Transceiver 200 includes
multiple independent transmit and receive chains. Transceiver 200
performs phased array beam forming using a phased array that takes
an identical RF signal and shifts the phase for one or more antenna
elements in the array to achieve beam steering.
Referring to FIG. 2, Digital Signal Processor (DSP) 201 formats the
content and generates real time baseband signals. DSP 201 may
provide modulation, FEC coding, packet assembly, interleaving and
automatic gain control.
DSP 201 then forwards the baseband signals to be modulated and sent
out on the RF portion of the transmitter. In one embodiment, the
content is modulated into OFDM signals in a manner well known in
the art.
Digital-to-analog converter (DAC) 202 receives the digital signals
output from DSP 201 and converts them to analog signals. In one
embodiment, the signals output from DAC 202 are between 0-256 MHz
signals. In an alternative embodiment, the signals output from DAC
202 are between 0-750 MHz signals.
Mixer 203 receives signals output from DAC 202 and combines them
with a signal from a local oscillator (LO) 204. The signals output
from mixer 203 are at an intermediate frequency. In one embodiment,
the intermediate frequency is between 2-15 GHz.
Multiple phase shifters 205.sub.0-N receive the output from mixer
203. A demultiplier is included to control which phase shifters
receive the signals. In one embodiment, these phase shifters are
quantized phase shifters. In an alternative embodiment, the phase
shifters may be replaced by complex multipliers. In one embodiment,
DSP 201 also controls, via control channel 208, the phase and
magnitude of the currents in each of the antenna elements in phased
array antenna 220 to produce a desired beam pattern in a manner
well-known in the art. In other words, DSP 201 controls the phase
shifters 205.sub.0-N of phased array antenna 220 to produce the
desired pattern.
Each of phase shifters 205.sub.0-N produce an output that is sent
to one of power amplifiers 206.sub.0-N, which amplify the signal.
The amplified signals are sent to antenna array 207 which has
multiple antenna elements 207.sub.0-N. In one embodiment, the
signals transmitted from antennas 207.sub.0-N are radio frequency
signals between 56-64 GHz. Thus, multiple beams are output from
phased array antenna 220.
With respect to the receiver, antennas 210.sub.0-N receive the
wireless transmissions from antennas 207.sub.0-N and provide them
to phase shifters 211.sub.0-N. As discussed above, in one
embodiment, phase shifters 211.sub.0-N comprise quantized phase
shifters. Alternatively, phase shifters 211.sub.0-N may be replaced
by complex multipliers. Phase shifters 210.sub.0-N receive the
signals from antennas 210.sub.0-N, which are combined to form a
single line feed output. In one embodiment, a multiplexer is used
to combine the signals from the different elements and output the
single feed line. The output of phase shifters 211.sub.0-N is input
to intermediate frequency (IF) amplifier 212, which reduces the
frequency of the signal to an intermediate frequency. In one
embodiment, the intermediate frequency is between 2-9 GHz.
Mixer 213 receives the output of the IF amplifier 212 and combines
it with a signal from LO 214 in a manner well-known in the art. In
one embodiment, the output of mixer 213 is a signal in the range of
0 to about 250 MHz. In one embodiment, there are I and Q signals
for each channel. In an alternative embodiment, the output of mixer
213 is a signal in the range of 0 to about 750 MHz.
Analog-to-digital converter (ADC) 215 receives the output of mixer
213 and converts it to digital form. The digital output from ADC
215 is received by DSP 216. DSP 216 restores the amplitude and
phase of the signal. DSPs 211 may provide demodulation, packet
disassembly, de-interleaving, FEC decoding, and automatic gain
control.
In one embodiment, each of the transceivers includes a controlling
microprocessor that sets up control information for DSP. The
controlling microprocessor may be on the same die as the DSP.
The Back Channel
In one embodiment, the wireless communication system includes a
back channel, or link, for transmitting information between
wireless communication devices (e.g., a transmitter and receiver, a
pair of transceivers, etc.). The information is related to the
beamforming antennas and enables one or both of the wireless
communication devices to adapt the array of antenna elements to
better direct the antenna elements of a transmitter to the antenna
elements of the receiving device together. The information also
includes information to facilitate the use of the content being
wirelessly transferred between the antenna elements of the
transmitter and the receiver.
In FIG. 2, back channel 220 is coupled between DSP 216 and DSP 201
to enable DSP 216 to send tracking and control information to DSP
201. In one embodiment, back channel 220 functions as a high speed
downlink and an acknowledgement channel.
In one embodiment, the back channel is also used to transfer
information corresponding to the application for which the wireless
communication is occurring (e.g., wireless video). Such information
includes content protection information. For example, in one
embodiment, the back channel is used to transfer encryption
information (e.g., encryption keys and acknowledgements of
encryption keys) when the transceivers are transferring HDMI data.
In such a case, the back channel is used for content protection
communications.
More specifically, in HDMI, encryption is used to validate that the
data sink is a permitted device (e.g., a permitted display). There
is a continuous stream of new encryption keys that is transferred
while transferring the HDMI data stream to validate that the
permitted device has not been changed. Blocks of frames for the HD
TV data are encrypted with different keys and then those keys have
to be acknowledged back on back channel 220 in order to validate
the player. Back channel 220 transfers the encryption keys in the
forward direction to the receiver and acknowledgements of key
receipts from the receiver in the return direction. Thus, encrypted
information is sent in both directions.
The use of the back channel for content protection communications
is beneficial because it avoids having to complete a lengthy
retraining process when such communications are sent along with
content. For example, if a key from a transmitter is sent alongside
the content flowing across the primary link and that primary link
breaks, it will force a lengthy retrain of 2-3 seconds for a
typical HDMI/HDCP system. In one embodiment, this separate
bi-directional link that has higher reliability than the primary
directional link given its omni-directional orientation. By using
this back channel for communication of the HDCP keys and the
appropriate acknowledgement back from the receiving device, the
time consuming retraining can be avoided even in the event of the
most impactful obstruction.
During the active period when the beamforming antennas are
transferring content, the back channel is used to allow the
receiver to notify the transmitter about the status of the channel.
For example, while the channel between the beamforming antennas is
of sufficient quality, the receiver sends information over the back
channel to indicate that the channel is acceptable. The back
channel may also be used by the receiver to send the transmitter
quantifiable information indicating the quality of the channel
being used. If some form of interference (e.g., an obstruction)
occurs that degrades the quality of the channel below an acceptable
level or prevents transmissions completely between the beamforming
antennas, the receiver can indicate that the channel is no longer
acceptable and/or can request a change in the channel over the back
channel. The receiver may request a change to the next channel in a
predetermined set of channels or may specify a specific channel for
the transmitter to use.
In one embodiment, the back channel is bidirectional. In such a
case, in one embodiment, the transmitter uses the back channel to
send information to the receiver. Such information may include
information that instructs the receiver to position its antenna
elements at different fixed locations that the transmitter would
scan during initialization. The transmitter may specify this by
specifically designating the location or by indicating that the
receiver should proceed to the next location designated in a
predetermined order or list through which both the transmitter and
receiver are proceeding.
In one embodiment, the back channel is used by either or both of
the transmitter and the receiver to notify the other of specific
antenna characterization information. For example, the antenna
characterization information may specify that the antenna is
capable of a resolution down to 6 degrees of radius and that the
antenna has a certain number of elements (e.g., 32 elements, 64
elements, etc.).
In one embodiment, communication on the back channel is performed
wirelessly by using interface units. Any form of wireless
communication may be used. In one embodiment, OFDM is used to
transfer information over the back channel. In another embodiment,
continuous-phase modulation (CPM) with low peak-to-average power
ratio is used to transfer information over the back channel.
Reduction of Power Consumption
In order to sustain very high data rates and low costs, a wireless
device may have multiple antennas that are adjusted in phase and
amplitude to focus the radio waves in a direction that maximizes
the useful power delivered to the receiver. However, for low power
devices operating at reduced ranges and/or reduced data rates,
using all of the power amplifiers in the transmitter to excite all
of the antennas will be wasteful of power. In accordance with one
embodiment, only a portion of the antennas are used in the
low-range situation and the power amplifiers associated with the
unused antennas are turned off to reduce the TX power usage. This
reduces the range somewhat, but at a great savings in power. For
example, if only one-half of the antennas are used, and hence
one-half of the power, the range is decreased by a factor of four.
In accordance with another embodiment, only a portion of the
antennas are turned off to reduce RX power usage. A wireless device
may include several antennas coupled to a receiver, a transmitter,
or both.
FIG. 4 is a flow diagram of one embodiment of a method for reducing
a power consumption of a wireless device using a portion of the
antennas of the wireless device based on the power source of the
wireless device. At 402, the type of power source of the wireless
device is determined. For example, the wireless device may detected
whether it is powered by a battery or an AC power supply. At 404,
once the device detects if it is battery or AC mains powered, it
automatically reduces the number of TX antennas that are used to
minimize power usage. The wireless device can operate with all the
antennas and power amplifiers when it is powered by the AC
mains.
FIG. 5 is a flow diagram of one embodiment of a method for reducing
a power consumption of a wireless device using a portion of the
antennas of the wireless device based on a user selection. If a
user is charging the battery of the wireless device or if the user
wants to run the wireless device for longer than is typical, they
may want to set it near a power outlet, which may or may not be
close to the display. In this case, the user can tell the device to
go to full power, thereby using all of the antennas for
transmitting the data, allowing the connection over a longer
distance. At 502, a user selection is determined. At 504, the
number of antennas used to transmit or receive is based on the user
selection.
In another embodiment, the wireless device decreases the number of
antennas used while maintaining the data rate and a desired signal
quality as illustrated in FIGS. 6 and 7.
FIG. 6 is a flow diagram of one embodiment of a method for reducing
a power consumption of a wireless device using a portion of the
antennas of the wireless device based on a received data rate and
signal quality. At 602, the wireless device may monitor the data
rate and signal quality of data received. At 604, if the quality of
the signal or the data rate is below a predetermined or preset
threshold, more antennas in the receiving wireless device may be
used.
FIG. 7 is a flow diagram of one embodiment of a method for reducing
a power consumption of a wireless device using a portion of the
antennas of the wireless device based on a feedback of data rate
and signal quality. At 702, the wireless device may receive a
feedback of data rate and signal quality received at another
wireless device at another location. At 704, if the quality of the
feedback signal or the data rate is below a predetermined or preset
threshold, more antennas in the transmitting wireless device may be
used. In accordance with one embodiment, the wireless device
monitors the channel conditions and changes the number of TX
antennas used on a continual, automatic basis to optimize
parameters such as power usage, performance, resistance to
interference, and/or performance per amount of power used. As the
link quality is reduced, the wireless device may utilize more TX
antennas for the link and as the link quality improves it may
decrease the number of TX antennas used. Thus in the case where the
source device is close to the display and has an unimpeded line of
sight link, the battery drain is minimized. At the same time, if
the link is temporarily blocked, the device can temporarily
increase the number of TX antennas that are used to maintain the
link quality at the expense of a temporary increase in the power
used. This automatic adjustment of power provides optimal use of
the finite energy available in the battery.
In another embodiment, the wireless device may select specific
antennas to be powered and specific antennas to be turned off, as
illustrated in FIGS. 8 and 9.
FIG. 8 is a flow diagram of one embodiment of a method for reducing
a power consumption of a wireless device using specific antennas of
the wireless device based on a received data rate and signal
quality. At 802, the data rate and signal quality is determined and
monitored. At 804, each antenna is evaluated to determine whether
to power it on or off in response to an increase or decrease in the
data rate and signal quality received at the wireless device.
FIG. 9 is a flow diagram of one embodiment of a method for reducing
a power consumption of a wireless device using specific antennas of
the wireless device based on a feedback of data rate and signal
quality. At 902, a feedback of the data rate and signal quality
received at another wireless device at another location is received
and monitored. At 904, each antenna is evaluated to determine
whether to power it on or off in response to an increase or
decrease in the data rate and signal quality of the feedback. The
wireless device may determine which TX antennas are capable of
sending the highest performance or lowest power-consuming signals.
This is important because the effective transmit performance of
antennas may vary depending on the relative position of the
antenna, environmental, and/or manufacturing factors. The wireless
device would then select exactly which would be the best antennas
to use (adjusting the selection from time to time) so as to
optimize the aforementioned parameters. This antenna selection can
be done based on the estimated channel between the transmit antenna
and the desired receiver. One example would be to use only the
antennas that give the strongest received signal.
In accordance with another embodiment, the wireless device may use
a narrower signal bandwidth for the reduced data rate to reduce
power usage. The wireless device may reduce the data rate and the
TX RF power by transmitting only those sub-carriers that have the
best link quality, or send a portion of the original image or video
stream as illustrated in FIGS. 10, 11, and 12.
FIG. 10 is a flow diagram of another embodiment of a method for
reducing a power consumption of a wireless device based on the
power source of the wireless device. At 1002, a power source of the
wireless device is determined. Based on the type of power source,
the wireless device may transmit a portion of the data, may reduce
the data rate, or may reduce a duty cycle at 1004.
FIG. 11 is a flow diagram of another embodiment of a method for
reducing a power consumption of a wireless device based on a user
selection. At 1102, a user power selection of the wireless device
is determined. Based on the user selection, the wireless device may
transmit a portion of the data, may reduce the data rate, or may
reduce a duty cycle at 1104.
FIG. 12 is a flow diagram of another embodiment of a method for
reducing a power consumption of a wireless device based on a
feedback of data rate and signal quality. At 1202, a feedback of
data rate and signal quality received at another wireless device at
another location is determined. Based on the feedback, the wireless
device may transmit a portion of the data, may reduce the data
rate, or may reduce a duty cycle at 1204.
Such portions could include skipping entire lines, specific pixels,
patterns of pixels, subsets of pixels and or a subset of the bits
per pixel. The pattern used or bits used can be selected
differently on the chrominance or luminance or the physical
location of the pixels in the displayed image.
In an uncompressed video signal, most of the information is
contained in the most significant bits (msbs) of each of the three
color signals. Much of the signal fidelity can be reconstructed by
sending only a portion of the bits used to encode the color for
each of the pixels. For example, if only the 2 most significant
bits of each byte for the three colors of the image are sent, the
data rate is reduced by a factor of four. At the receiving end, a
variety of algorithms can be used to reconstruct the image. The
missing least significant bits (lsbs) could be filled with random
data to avoid creating artifacts in the image. Alternately, each
the missing lsbs could be detemined from the msbs that are sent. In
another embodiment, the msbs from one or more adjacent pixels can
be used with the msbs of the pixel to calculate the lsbs required
to complete the pixel data.
Once the data rate has been reduced, the device can then transmit
for less time overall, reducing the average power usage.
Alternately, the device could reduce both the RF transmit (TX)
power and the data rate to reduce both the average and peak power
usage in the device. Because the data rate is reduced along with
the RF TX power, the link margin can remain the same while reducing
the energy and power required from the battery.
The highest quality HD signals, currently 1080p, operate in
progressive scan mode. What that means is that the entire video
frame is sent at the frame rate, which is approximately 30 Hz
(Other rates are supported, including 24 Hz, and for lower
resolutions, 60 Hz. In addition, rates of 24 Hz/1.001, 30 Hz/1.001
and 60 Hz/1.001 are defined from some resolutions.) A lower quality
version at the same resolution, 1080i, operates at half of the data
rate of 1080p. It does this by sending alternate lines of the video
frames at the same frame rate. Thus the data on the screen is
updated at the same rate, but only 1/2 the data at a given time.
For example, a 1080i video stream might would send the odd lines
from one video frame and the even lines from the next one,
alternating odd and even at the 30 Hz update rate.
For the mobile device transmitting video content, it can save power
by taking progressive scan stream and converting it to interlaced
by dropping one half of the video lines at the transmitter. At the
receiver, the previous video frame, only one-half the size of a
full progressive frame because it is the interlaced version, is
stored. The receiver then provides as output the previous frame
with the current frame as a complete video frame. In one
embodiment, the transmitting system sends the data at the higher
data rate, but uses one-half the time, reducing the average power
required from the battery by about one-half. In another embodiment,
the transmitting system reduces both the RF TX power and data rate
by one-half, reducing both the peak power and the average power
required from the battery. In a further embodiment, either of these
power reduction techniques can be applied in a system that senses
when the transmitter is plugged in or operating off of the battery
and adjusts the parameters to save power, either due to user
intervention or automatically based on the state of the input
power.
Another embodiment either transmits at a reduced duty cycle or
reduces the power and data rate automatically in response to
changing channel conditions and power source. When the device is
plugged in, it operates at the full data rate. When the device in
battery powered and is experiencing good wireless link conditions,
it operates with either reduced duty cycle or reduced RF TX power
and data rate. If the wireless link conditions are poor, the device
either temporarily increases the RF TX power or repeats lost radio
transmissions to improve the reliability of the data delivery.
In another embodiment, the device signals to the display to operate
at a lower resolution, frame rate, color depth, or fidelity so as
to reduce the amount of data that it expects the device to send;
thereby, reducing power consumption.
In a further embodiment that applies to all of the previous ones,
the receiver applies one of the many de-interlacing, concealment,
and/or transcoding algorithms to reduce the visual effect of the
artifacts created by changing from progressive scan to interlaced
scan.
In the case where the mobile wireless device needs to display an
image, for example a DSC wirelessly presenting images on a display,
the refresh rate can be very slow, on the order a few times a
second (<6 Hz) because display is not showing motion. In this
case, the transmitting device will reduce the refresh rate from 24,
30 or 60 Hz to a much lower rate, e.g., 3 or 6 Hz, providing a
potential power savings of 10 to 20 times. The receiver then stores
the video frame in memory and then provides it to the output at the
desired refresh rate by simply repeating the same data. In one
embodiment, the transmitter reduces the duty cycle for sending
data, but using the higher data rate. This allows the transmitter
to be active only a portion of the time, reducing the average power
required from the battery. In another embodiment, the transmitter
reduces both the RF TX power and the data rate, thereby reducing
both the peak and average power required from the battery. In
another embodiment, the device can use the method of reduced
refresh rate for still images, either reduced duty cycle or reduced
RF TX power and data rate, depending on the state of the power
source for the device, either by user intervention or by
automatically selecting the method by sensing the power source.
Another embodiment of this invention is one in which the
transmitter sends subset of the pixels only and the receiver
reconstructs the signal before passing it to the display. In
another embodiment the receiver applies one of the many
de-interlacing, concealment, and/or transcoding algorithms to
reduce the visual effect of the artifacts created by send a reduced
number of the pixels. One such arrangement could be a
"checkerboard" in which every other pixel is sent with the first
pixel that is not sent is either the first or second pixel,
alternating between lines, e.g., line 1, 3, 5, . . . skip odd
numbered pixels, lines 2, 4.6 . . . skip even numbered pixels.
The pixels around the edge of the screen are often viewed only by a
person's peripheral vision and so they could be skipped and
replaced with random data. Also, the content is typically focused
to place the most important part of the image at the center, so
pixels around the outer edge could be skipped or sent with less
resolution, reducing the required bandwidth. In one embodiment, a
subset of the pixels in the video frame or image that are on the
outer periphery of the frame or image are not sent or are sent with
lower resolution.
In a further embodiment that applies to all of the previous ones,
the receiver applies one of the many de-interlacing, concealment,
and/or transcoding algorithms to reduce the visual effect of the
artifacts created either sending fewer pixels or fewer bits for any
of the pixels.
For all of the previously recited methods, the system may use a
narrower signal bandwidth for the reduced data rate to reduce power
usage. For example, this can reduce the power required for the
various parts of the radio, e.g., ADC, DAC, analog baseband,
digital baseband and power amplifiers.
For all of the previously recited methods, the system may reduce
the data rate and TX RF power by transmitting only those
sub-carriers that have the best link quality.
In accordance with another embodiment, the wireless device may
operate by alternating data processing and radio transmission. For
the mobile device, the battery life is determined not just by the
power used by the wireless connection, but also by the power used
in the rest of the system. For example, a DVC needs to provide
power to read the tape. In all of these devices, the output is
uncompressed video because most displays do not have decompression
capability and if they do, they may not have the correct decoder
for the format of the data on the device. Thus for maximum
compatibility, the video or still image is decompressed and
reformatted prior to being sent to the display. This decompression
can use a significant amount of power and if the decompression runs
at the same time as radio is transmitting, then the overall peak
power is increased. A battery, in addition to having a finite
amount of energy, also has a finite power that can be delivered due
to the characteristics of the battery. If the combination of the
power required to decompress the data plus the power required for
transmitting the data exceeds the power limit for the battery, then
the system will not work. In addition, all batteries have an
internal resistance and the power lost (and converted to heat) is
proportional to the square of the current. Thus if the current can
be cut in half, the power lost due to the internal resistance of
the battery would be reduced by one-quarter.
With high radio data rates available and lower application data
rates, it is possible to schedule the decompression and other
processes to occur only when the radio isn't transmitting.
Likewise, when the device is decompressing the data, the
transmitter in not operating, so that the peak power required is
reduced. In one embodiment, the radio provides a signal to the
device that indicates when the radio is transmitting. When the
device receives this signal, it postpones power intensive tasks
until the radio signals that it is either idle or in receive mode.
This scheduling allows the device to reduce the peak power required
for the application. For all of the previously recited embodiments,
a system in which any processing including video or image
processing is scheduled to occur when the radio is not transmitting
or receiving.
Whereas many alterations and modifications of the present invention
will no doubt become apparent to a person of ordinary skill in the
art after having read the foregoing description, it is to be
understood that any particular embodiment shown and described by
way of illustration is in no way intended to be considered
limiting. Therefore, references to details of various embodiments
are not intended to limit the scope of the claims which in
themselves recite only those features regarded as essential to the
invention.
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